1. Field of the Invention
The present invention relates to hyaluronate based compositions and cosmetic formulations.
2. The Prior Art
Hyaluronic acid (hereinafter referred to as "HA") as well as its salts, such as sodium hyaluronate (hereinafter referred to as "NaHA") is a known, naturally occurring high viscosity glycosaminoglycan having alternating .beta. 1-3 glucuronidic and .beta. 1-4 glucosaminidic bonds. The molecular weight of this material is generally within the range of 50,000 to 8,000,000 (although there are reports of HA having molecular weights as high as 13,000,000) depending on the source, method of isolation and method of determination. It is found in animal tissue, e.g. in umbilical cord, vitreous humor, synovial fluid, rooster combs, pathologic joints, group A and C hemolytic streptococci and in skin.
The isolation and characterization of HA is described in Meyer et al, J. Biol. Chem. 107, 629 (1934); J. Biol. Chem. 114, 689 (1936); Balazs, Fed. Proc. 17, 1086 (1958); Laurent et al; Biochim. Biophys. Acta 42, 476 (1960). The structure of HA was elucidated by Weissman et al, J. Am. Chem. Soc. 76, 1753 (1954) and Meyer, Fed. Proc. 17, 1075 (1958).
For certain uses, extremely pure HA preparations are required; see, for example my U.S. Pat. No. 4,141,973, which describes the preparation and uses of such an HA.
It is also known that the softness and flexibility of the stratum corneum, which is the upper layer of the skin, depends on the moisture content of the intercellular channels in this layer. Thus, cosmetic chemists and medical researchers have, long sought to find ways of restoring these vital qualities of the skin when they are lost, as occurs with the natural aging process, and in cases of extreme dryness.